The sample was aerosolized in a chamber and collected onto
Whatman 1 filters over a 4 h period. Acid digestion was carried
out on 10 mm punches taken from the filters, and
determination of Fe and Ni was accomplished on the μPAD
(Figure 6b). Copper levels in the sample were too low to
detect; however, they fall well below limits set for exposure, as
discussed above. Agreement between actual and measured
values is shown in Table 3 and indicates that the acid digestion